I am installing an ls1 into my 85 vette,almost done,
what i need help with is iat sensor,
where to install it, from throttle body i have a silacone hose then maf and then a cone filter.
I was told to drill a hole in the rear of the cone filter and put iat there, is this rite

 

you could do that or use a truck MAF with the intergrated IAT

 

I'd say as close to the TB as is reasonable. You don't want to 'trick' your tune by feeding it false IAT readings by putting it all the way out at the filter. Or just keep it simple and go with oange's suggestion.

You could always double check that the MAF you have aquired already doesn't already have one hiding inside.